In a liquid crystal display panel, a TFT (Thin Film Transistor) substrate and a counter substrate are often supported by a spherical spacer or a columnar spacer arranged between them. As a result, a predetermined thickness of a liquid crystal layer (henceforth, referred to as a cell gap) is obtained.
When a spherical spacer is used, the fixing characteristic between the spacer and the substrates is weak. Therefore, in a liquid crystal display device in which the cell gap is supported by spherical spacers, the spherical spacers are easily moved by a vibration such as when it is transported. Moving of the spherical spacers causes an indication defect such as a leak of light, degradation of contrast and lack of uniformity of the cell gap. A spherical spacer arranged in an indication area causes an alignment defect in its peripheral part. As a result, degradation of contrast occurs.
Moreover, for a liquid crystal display panel or the like supporting an animation, fast response is required. One of means to realize fast response is to make a cell gap small. However, in order to form a cell gap which is sufficiently small, a spherical spacer whose grain diameter is small and whose variation in the grain size is small is needed. Acquisition of such spherical spacer is not easy.
On the other hand, in the case of a liquid crystal display device in which a columnar spacer is arranged in a light shielding portion, the problem that a spacer is moved by a vibration and the like does not occur. This is because a columnar spacer is fixed on a CF substrate firmly. Moreover, by arranging a columnar spacer in a light shielding portion, contrast of a panel also improves. A columnar spacer can be made short sufficiently compared with a spherical spacer. Therefore, along with requirements for a liquid crystal display device with higher contrast and a faster response in recent years, products using a columnar spacer are increasing.
However, when external stress such as rubbing the panel surface is added to a panel using a columnar spacer, the following problem occurs. That is, a columnar spacer fixed on either one of substrates is moved by glide motion on the surface of the other substrate facing the former.
A columnar spacer generally forms a cell gap in the state that it is compressed by several %. Therefore, a force is always added between the surface of a columnar spacer and the surface of a substrate which the columnar spacer touches. Even when a force added from outside disappears, it is often difficult to return to the original state because of friction of the surface of the substrate which the columnar spacer touches. In this case, a stress remains in the two substrates facing each other. Therefore, there occurs a problem that light leak is caused in a black screen.
A liquid crystal display device shown in FIG. 16 is disclosed in Japanese Patent Application Laid-open Publication No. 2005-242297. In the liquid crystal display device shown in FIG. 16, a convex step film is formed onto a position corresponding to a columnar spacer.